1- (noun) A Facebook profile (the spy) that is used to gather information about users of a certain demographic (the user), particularly people applying for a job in a large company. The spy will be reimbursed by the hiring company for discovering negative information about the user resulting in the user being barred from employment

2- (noun) A person caught in the act of observing your Facebook activities at a public location, particularly at a college study commons or library. Usually synonymous with a person who behaves as if they were invisible, but whom actually stands out due to poor hygiene, off appearance, or generally creepy mannerisms.

3- (verb) To log into the Facebook account of another person without their knowledge to monitor their private activities, such as message history. An act marked by jealousy, suspicion, and lack of trust.

1-
Jake: Hey man, how did your job interview with company-X go?
Steve: It was going great until they asked me to friend Becky in human resources... I got nervous when I thought about all those pictures from freshman year.

2-
Corey: Yeah, I'm studying at the library, I think I'll be ready for the test.
Sarah: Hey me too. Actually, where are you? This smelly guy near me keeps facebook spying on me and I need to move.

3-
Mike: Hey Nick, so I think my girlfriend thinks I am cheating on her.
Nick: Uh... ok?
Mike: Yeah, so I think she has my facebook password and I think she has been checking my messages.
Nick: So change your password.
Mike: No, I wanna find out if she has been facebook spying on me.

Nick: Soooo ask her, or ask mutual friends to find out.
Mike: Well I can't ask her, then she'll know I'm onto her. I wanna trap her somehow.
Nick: Ummm.... You could just send ridiculous messages to yourself like "you have aids" and see if she reacts... Actually, instead, send yourself a message that a specific family member has passed away, then try to get her console you and maybe you can get her to trip up and mention message specifics? I donno.

When someone sends you an invite on Facebook and after noticing their inactivity a few months later you check their profile only to discover that they have no information/misinformation on their page and are only using it to check your Facebook statuses, pictures, and posts.

"Julian is such a Facebook Spy. He always knows what I post and where I've been, but his Facebook page is still blank after 6 months and I'm his only friend on Facebook. What a freak!"